Introduction: Resurrecting a 38 Year Old Motorcycle

Picture of Resurrecting a 38 Year Old Motorcycle

I was looking for a fall project, and decided to take on resurrecting a 1972 Honda SL125 that had been sitting in storage for 18 years.  The bike had been stored near some swimming pool chemicals and fertilizer, and every metal surface was either rusted (steel) or oxidized (aluminum).  The bike would not have been a suitable candidate for restoring to original, but was a good candidate for "resurrecting" as a rider.

The good news was that the motor and transmission was in good shape, with 9,000 miles on the odometer.  The clutch plates were stuck, but about an hour of rocking the bike back and forth with the bike in gear and the clutch lever pulled finally broke them free. 

The carburator was beyond redemption -- the idle circuit and air bleed were too corroded to rebuild, but an ebay carb took care of that problem.  I also replaced the horn, the ignition switch, and one of the rear shocks -- again, using ebay.

So, my instructable is focused mainly on rust and corrosion removal, which took the better part of two months to complete.

Step 1: Removing Stuff

Picture of Removing Stuff

I began by removing the seat, gas tank, fenders, exhaust system, side covers, and the rear view mirrors.

The seat was held on by two nuts, and once removing these I simply lifted up the rear of the seat and pulled the front loose from its bracket.  With the seat removed, the gas tank (after removing the fuel line) pulled free from its front bracket.

The front fender was held by three bolts, which I wound up having to twist off (too corroded to come loose, even with plenty of penetrating oil).  I drilled out these broken bolts.

The rear fender was held on by four bolts, and once removed I could get to the bolts that held the tail light/license bracket.  The wire for the tail light unit simply unplugged from the wiring harness.

The exhaust system surprisingly came free without breaking any of the studs that held it on.

The side covers were designed to simply pop on and off, so they came off easily, and the rear view mirrors unscrewed from their handlebar mounts.

Throughout all of the disassembly process I carefully kept track of all loose parts by putting them in labeled sandwitch bags.

Step 2: Preparing the Frame

Picture of Preparing the Frame

I began the rust removal process with the frame.  I decided that since everything was highly visible on this bike, I would not need to remove the motor -- I'd just work around it.

Beginning with 120 grit shop rolls, I sanded every square inch of the frame, then switched to 220 grit.  Once all rust was removed, I painted the frame with a rust stopping primer.  I used a brush to apply the primer, since I had decided to paint the frame with a hammered finish enamel.  I decided on using the hammered finish, since the frame was too pitted for a really smooth finish.

Step 3: Exhaust System

Picture of Exhaust System

The exhaust system was badly rusted, but still sound.  After sanding and grinding away the rust, I used an automotive high-temp primer, followed by a high-temp flat black enamel.

Because of the size of the exhaust system, I was unable to bake the paint on in my wife's oven, so I baked it by periodically running the engine for 10 minutes after the bike's fuel tank was reinstalled.

Throughout this entire "resurrection" process, all parts that had previously been chrome plated were sanded and painted, including the exhaust system.  There was simply too much pitting for re-chroming.

Step 4: Tackling Rusty Rims

Picture of Tackling Rusty Rims

The rims on this project bike were in terrible shape.  The front wheel was entirely coated in rust, including every spoke.  Fortunately, however, this was just surface rust and pitting -- the integrity of the rims was still sound.

I started with 120 grit paper and worked my way down to 220 grit on the rims and the spokes.  All-in-all I spent 7 hours sanding the front wheel and 3 hours sanding the rear wheel.

Before sanding the rims, I tried every rust-removing chemical I coudl find (including using cola!).  Unfortunately, the rust was just too profound for chemical removal, so I had to do it the hard way.

Once all the rust was removed, I sprayed each wheel with primer, then the hammered finish enamel.

Step 5: Repairing the Gas Tank

Picture of Repairing the Gas Tank

The gas tank had numerous problems.  First, the inside was rusty and coated with 38 years of gunk.  The petcock was clogged, and the tank had four dents in it.

Using a drill bit as a hand reamer, I unplugged the galleys in the petcock, then soaked it in carb cleaner.

For the inside of the tank, I first put a handful of nuts an bolts in it along with about a quart of degreaser, plugged the inlet and outlet, then rocked the tank back and forth and up & down for about 30 minutes to loosen the crud inside.  Next I used a DIY commercial cleaning coating process which entailed soaking the inside of the tank in a weak acid solution for 8 hours, then using a neutralizer, then a permanent coating.

After taking care of the tank's insides, I then began work on the part that "shows."  I used bondo to fill the four dents, carefully sanding and feathering the filler to the lines of the tank.  Then I applied primer, then paint.

While the finaly coat was drying, I used a small knife blade to scrape away the rust from the tank's logo, then touched up the paint on the logo with an artist's brush. 

Before reattaching the logo, I applied stair tread (sort of like a rough, rubbery tape) to the sides of the tank for decoration, then screwed the logo back on each side.

I realize this is not exactly how the original looked, but remember -- this is a resurrection, not a restoration!

Step 6: Fenders, Side Covers, Miscellaneous

Picture of Fenders, Side Covers, Miscellaneous

All removed parts were sanded, primed, and painted.

The side covers were the only plastic items on the bike, and befrore painting I fixed a couple of cracks in one of them using hot glue (on the back side).  Then I sanded, primed, and painted them just like the metal parts.  The logos on the side covers were cleaned up and touched up.

While parts were drying, I recovered the seat with a seat cover I bought off of ebay.

Step 7: Reassembly

Picture of Reassembly

The reassembly basically involved doing everything in reverse.  It is at this point when I was really glad I took the time to put all loose parts in labeled sandwitch bags!

Step 8: New Carb

Picture of New Carb

I finally decided to replace the carburator.  I just couldn't get it adjusted due to the bad corrosion that had built up.  A new carburator from ebay made the bike run like new.

Step 9:

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The project is finished!  I spent quite a bit of time on this bike (7 hours just sanding one wheel!), but very little money.  All-in-all I think I spent around $300 on parts and supplies.

I'm not a motorcycle mechanic, but am reasonably handy with tools.  When I began this project I purchased a Clymer manual, which I found indespensible.


scottjanousek (author)2017-02-12

Nice result!

I have a 1973 SL350k2 barn find I'm considering on restoring. This is an inspiring project, even if the one I am looking at is not salvageable for riding (i.e. not sure if the engine is viable) ... for parts, perhaps.

I have sent an email if you would like to feed me some input on your total estimated time on the project.

BTW: Did you pay anything for the barn find bike before you started the project?

chillipassion (author)2016-10-25

Hi can you tell me how to get my fork stanchions clean on my SL125 that are rusted.

knife141 (author)chillipassion2016-10-26

Wire brush, fine sandpaper, rust removing chemicals.

Nikki8542 (author)knife1412016-11-21

Hello I'm restoring a 1979 RM 50 there is rust on front forks. Handle bars and rims , will your method work for all of those , otherwise the bike is in great shape just body work

chillipassion (author)knife1412016-10-26

Hi il post a thread on my bike. So you can see what I'm dealing with.

Colin McLain (author)2016-11-19

Thankyou for the information on this topic! I have been considering resurrecting or restoring an old Honda CB500T that has part of it scattered across my families land. For instance, the frame is in a deep gully, but the motor (Which runs) is in my dads shop. The frame is quite rusted from sitting outside for roughly 30 years, though parts for old CB500T's are extremly inexpensive! Anyways, thankyou again for the great description!

MichaelI39 (author)2016-03-02

Should have tried "Metal Rescue". It will remove rust that heavy just by soaking for a few hours. Can get it at Home Depot or even Walmart. Comes in qt., Gal., and 5- gallon buckets. google it and watch their videos.

DevTheHam (author)2015-11-24

how did you apply the enamel finish? spray or brush? sorry if it's a bit of a noob question, but I just dug up an old motorcycle in a similar condition to yours, and I don't want to go through all of the trouble of removing the motor and stuff to repaint the frame.

knife141 (author)DevTheHam2015-11-24

I painted the frame with a brush, and everything else with a rattle can.

DevTheHam (author)knife1412015-11-25


katie.vanderwende (author)2015-06-01

Hey just wondering what carb setting did you use? I am trying to fine tune my carb yet everyone insists 2 turns out from seated, which I can't get the bike to even start, much less run very well. I am currently running extremely lean to where the air/fuel setting is almost flush with the outer lip

<<< my wife's FB.....

Be sure you don't have any air leaks.

2 turns out is roughly what I used.

TheMadScientist (author)2015-07-21

never say too corroded to rebuild until you put it in a pot of boiling water.

CollinF1 (author)2015-07-02

Nice job, looks great!

I'm curious to know how you did the front forks. I'm restoring a 1974 XL175, and the forks have a bit of surface rust. You ended up painting yours black I see, did you have any problems with oil leaking? How did you maintain suspension without having to replace the forks altogether?

Thanks for the instructable. Again, nicely done!

kingkelly (author)2015-06-23

DonnaL5 (author)2015-05-26

hi i was just winding if you think my rims are too rusted to restore? i was going to blast them then paint them- the inner that is, the poke side is in good condition. thanks

knife141 (author)DonnaL52015-05-26

It's hard to tell from the photo, but it looks to me like the rust has eroded the metal in some places. If it's just light surface rust, you might be ok. If it has actually eaten into the structure, I wouldn't risk it.

DonnaL5 (author)knife1412015-05-29

Yeah it has eaten away at it a bit, best replace them then. thanks

kingofrandom92 (author)2015-03-16

1972 Cl350 4 years of on an off work. almost done but when are we ever "done"

egossar (author)2015-02-03

I'm in the process of restoring a family owned 1971 SL175 that has a unique story, was stolen, recovered and never finished and now I am finishing it.. Just missing some odds and ends yet. Great job on that CL!

AndrewsY (author)2015-01-27

Awesome job, awesome. My son and I have just started work on a 1981 Yamaha SR250 and if she ends up looking anywhere as nice as the bike you did he'll be a happy chappy :-D

dpatterson13 (author)2015-01-18

Love the SL's! Quite a feat you performed! Great job!

strapman (author)2014-12-20

So cool to see other garage mechanic's (not pro's) ressurecting these old bikes! I just finished a 1971 CB 450 that was painted red by previous owner. Brought it back to original candy gold, every nut/bolt in my hands, tackling dirt/rust everywhere. Done now, but dont know what to do with it! Runs great, but i have an older Goldwing thats my main ride---this lil thing is like a scooter!

scottyrebels55 (author)2014-11-06

You. Are. The. Man!
So cool. Thank you. Restoring a '72 cb350.
Its not in nearly as neglected condition as your bike, though it had been sitting and forgotten since 1977. For that, I am grateful. I'm sure you know how I feel. Very helpful info for me.

JhaydenA (author)2014-11-02

Looks mint

ghiabb (author)2014-06-20

Well Done!!!

jesucka87 (author)2014-04-27

I cant figure out how to remove my petcock, I got the bottom off and now i see a screen but no screw

sesvashon (author)2014-04-17

Thanks for sharing this post and looks like a great project.

I have a 75 Honda CB360T I'm working on. thanks for the tips!

Keep the old machines running!

jesucka87 (author)2014-03-31

I started working on this same style/color bike today :)

dgramo (author)2014-03-10

Bringing old bikes back to life is so rewarding. I am currently bringing a DRZ400 back to life and then I am onto a 1971 Kawasaki G3SS.

mrlunna13 (author)2011-08-19

Can anybody direct me on how to loosen up a seized engine?
Are there any "ibles" in here about seized engines? I looked but can't find one.
Mr. Lunna XIII

godson1952 (author)mrlunna132013-12-29

I know it's been 2 years but What I do use Diesel fuel Heated CAREFULLY!!!!, then pour it down the spark plug holes the replace the plugs then leave it sit over night.Then remove plugs to see if it will turn over .It works for me but sometime I leave sit for a good month in in a shop on a hot summer.

jesucka87 (author)2013-06-14

I HAVE THE SAME BIKE! Thanks for the instructable!!!!!

ArcAngel27 (author)2012-10-08

Hey, next time you have a dent in the tank, try using a blood pressure cuff. Roll it up real tight and stick it through the fuel fill hole. Then all you have to do is pump it up tight and it will pop the dents out. It works great if the dent is in the side and not on the curve of the tank.

harthoppy (author)2012-09-30

Coke a cola and tin foil removes rust like a champ !

lingg (author)2012-06-13

For me Step #1 is: Get the thing running first (if only down the driveway and back).
Then you know wether it's worth it to spend time and money on. Having made this mistake far too many times, I have to ride it before I even clean it! Although taking stuff apart is a good way to see how it works...I would do the bare minimum to get it running first before taking it apart and painting it. Beware of the Money Pit!

Kurokami (author)2012-03-06

Your sl125 turned out really well, I hope to resurrect my '65 Honda Trail 90 for the second time since my brother blew the top end.

7070x (author)2012-01-31

looking acutely sweet there.

I own a 1978 Honda CB 100. Been on the dock for the last two weeks. Same idea: resurrecting. Bit hoping to rejuvenate or mind you, swap off, with Chinese-made of Honda GL Pro series. In my area, that Honda SL125 is used mainly for Forest Rangers. Hard to get by these days, when found, such restored...err resurrected bike with original/genuine parts costs definitely a fortune !

Super great job !

bighamms (author)2010-05-13

Can you tell me the name & cost of the system you used for the tanks interior?

milesduggan (author)bighamms2011-08-19

Ps. its like $40 but it goes a long way!

milesduggan (author)bighamms2011-08-19

Don't use "Kreem" it is terrible! I had to redo my tank because it started to break down. I followed the instructions to the letter. An acquaintance of my told me it doesn't hold up well to fuel which makes no sense to me but I saw it first hand. He recommended a product called "Phenol Novalac" by "Caswell". Look up their website, its a great tank sealer! I used it and am blown away how easy it was to use and the results I got!

knife141 (author)bighamms2010-05-14

I used a product called Kreem, purchased at a motorcycle shop.  Don't recall the cost.

milesduggan (author)knife1412011-06-25

I think the kreem is like $20 for just the sealer. Pretty sure the whole 3 step kit is $50(acid wash, conditioner, and sealer).

milesduggan (author)2011-06-25

Ugh I hate cleaning gas tanks! I am in the process of fixing up a 1975 Honda CB360(got it for $500) and all it needs is a good cleaning(carbs, gas tank, motor) and new fluids. The gas tank is a little rusty inside and I have been procrastinating on getting it done. Well looks like the July 4th weekend is as good as any.

mrlunna13 (author)milesduggan2011-08-19

did you de-rusted your tank? I had the same problem. My tank was more than 40 years old. no paint, just rust. I did electrolysis on it. It looks awsome!!
You should try that if you haven't already. It really works wonders, and no fumes or harsh chemicals.
Here's the before and after. I just rinsed it with a hose.

milesduggan (author)mrlunna132011-08-19

Holy crap! What a difference! I did use the phosphoric acid to do my tank and it worked great, I just looked like a haz mat worker in the process. lol. Great job on your tank! Wish I would have gone your route although my results were just as good, just a little more work.

OmegaRacer (author)2011-07-31

everything perfect, but the engine has to be either painted or sand blasted.

gonlgn (author)2010-11-30

why don't you try to sand your engine with 1000cc sand paper it will make your engine shine or buffing will much easier . . . i Like your project . .

ac-dc (author)gonlgn2011-07-07

Sanding an engine is very very tedious, better to sandblast it instead.

About This Instructable




Bio: I enjoy taking a pile of junk and making something unusual out of it. I like wheeled vehicles, and currently own two motorcycles, two electric ... More »
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